NUMERICAL MODELING OF THE VERTICAL HEAT TRANSPORT THROUGH THE DIFFUSIVE LAYER OF THE ARCTIC OCEAN

Abstract

The Arctic Ocean has been a subject of increasing interest in recent years due to the reduction of the sea-ice thickness and spatial coverage and its implications for climate change. The future state of the Arctic is likely to be linked to vertical heat transport by microscale processes, specifically, double-diffusive convection. A series of realistic three-dimensional direct numerical simulations (DNS) were conducted to assess the vertical heat transport through thermohaline staircases in the Arctic region. Results revealed that vertical fluxes exceeded those of extant four-thirds flux laws by as much as a factor of two, and suggest that the 4/3 exponent requires downward revision. Results also showed that two-dimensional DNS can provide an accurate approximation of heat fluxes when the density ratio is sufficiently large. DNS results also reveal that the models with rigid boundaries result in heat flux estimates that are lower than those from models with periodic boundary conditions. Finally, the DNS-derived flux law was applied to Arctic data and results supported the conclusion that lab-derived flux laws significantly underestimate heat flux. All of these results suggest that vertical heat transport due to double-diffusive convection is a significant contributor to the measured reduction of Arctic sea-ice.